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From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH v1 15/29] virito-mem: document Sub Block Mode (SBM)
Date: Mon, 12 Oct 2020 14:53:09 +0200	[thread overview]
Message-ID: <20201012125323.17509-16-david@redhat.com> (raw)
In-Reply-To: <20201012125323.17509-1-david@redhat.com>

Let's add some documentation for the current mode - Sub Block Mode (SBM) -
to prepare for a new mode - Big Block Mode (BBM).

Follow-up patches will properly factor out the existing Sub Block Mode
(SBM) and implement Device Block Mode (DBM).

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 drivers/virtio/virtio_mem.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index faeb759687fe..fd8685673fe4 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -27,6 +27,21 @@ static bool unplug_online = true;
 module_param(unplug_online, bool, 0644);
 MODULE_PARM_DESC(unplug_online, "Try to unplug online memory");
 
+/*
+ * virtio-mem currently supports the following modes of operation:
+ *
+ * * Sub Block Mode (SBM): A Linux memory block spans 1..X subblocks (SB). The
+ *   size of a Sub Block (SB) is determined based on the device block size, the
+ *   pageblock size, and the maximum allocation granularity of the buddy.
+ *   Subblocks within a Linux memory block might either be plugged or unplugged.
+ *   Memory is added/removed to Linux MM in Linux memory block granularity.
+ *
+ * User space / core MM (auto onlining) is responsible for onlining added
+ * Linux memory blocks - and for selecting a zone. Linux Memory Blocks are
+ * always onlined separately, and all memory within a Linux memory block is
+ * onlined to the same zone - virtio-mem relies on this behavior.
+ */
+
 enum virtio_mem_mb_state {
 	/* Unplugged, not added to Linux. Can be reused later. */
 	VIRTIO_MEM_MB_STATE_UNUSED = 0,
-- 
2.26.2

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  parent reply	other threads:[~2020-10-12 12:55 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12 12:52 [PATCH v1 00/29] virtio-mem: Big Block Mode (BBM) David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 01/29] virtio-mem: determine nid only once using memory_add_physaddr_to_nid() David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 02/29] virtio-mem: simplify calculation in virtio_mem_mb_state_prepare_next_mb() David Hildenbrand
     [not found]   ` <20201015040204.GB86495@L-31X9LVDL-1304.local>
2020-10-15  8:00     ` David Hildenbrand
     [not found]       ` <20201015100009.GH86495@L-31X9LVDL-1304.local>
2020-10-15 10:01         ` David Hildenbrand
     [not found]   ` <CAM9Jb+h=2Wg3qAggjAfBf7yyvL9HU6xns7_giJfw6smkCAJ6SQ@mail.gmail.com>
2020-10-16  9:00     ` David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 03/29] virtio-mem: simplify MAX_ORDER - 1 / pageblock_order handling David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 04/29] virtio-mem: drop rc2 in virtio_mem_mb_plug_and_add() David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 05/29] virtio-mem: generalize check for added memory David Hildenbrand
     [not found]   ` <20201015082808.GE86495@L-31X9LVDL-1304.local>
2020-10-15  8:50     ` David Hildenbrand
     [not found]       ` <20201016021651.GI86495@L-31X9LVDL-1304.local>
2020-10-16  9:11         ` David Hildenbrand
     [not found]           ` <20201016100211.GI44269@L-31X9LVDL-1304.local>
2020-10-16 10:32             ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 06/29] virtio-mem: generalize virtio_mem_owned_mb() David Hildenbrand
     [not found]   ` <20201015083234.GF86495@L-31X9LVDL-1304.local>
2020-10-15  8:37     ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 07/29] virtio-mem: generalize virtio_mem_overlaps_range() David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 08/29] virtio-mem: drop last_mb_id David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 09/29] virtio-mem: don't always trigger the workqueue when offlining memory David Hildenbrand
     [not found]   ` <20201016040301.GJ86495@L-31X9LVDL-1304.local>
2020-10-16  9:18     ` David Hildenbrand
     [not found]       ` <20201018035725.GA50506@L-31X9LVDL-1304>
2020-10-19  9:04         ` David Hildenbrand
     [not found]           ` <20201020004130.GB61232@L-31X9LVDL-1304.local>
2020-10-20  9:09             ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 10/29] virtio-mem: generalize handling when memory is getting onlined deferred David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 11/29] virtio-mem: use "unsigned long" for nr_pages when fake onlining/offlining David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 12/29] virtio-mem: factor out fake-offlining into virtio_mem_fake_offline() David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 13/29] virtio-mem: factor out handling of fake-offline pages in memory notifier David Hildenbrand
     [not found]   ` <20201016071502.GM86495@L-31X9LVDL-1304.local>
     [not found]     ` <20201016080046.GA43862@L-31X9LVDL-1304.local>
2020-10-16  8:57       ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 14/29] virtio-mem: retry fake-offlining via alloc_contig_range() on ZONE_MOVABLE David Hildenbrand
2020-10-12 12:53 ` David Hildenbrand [this message]
2020-10-15  9:33   ` [PATCH v1 15/29] virito-mem: document Sub Block Mode (SBM) David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 16/29] virtio-mem: memory block states are specific to " David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 17/29] virito-mem: subblock " David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 18/29] virtio-mem: factor out calculation of the bit number within the sb_states bitmap David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 19/29] virito-mem: existing (un)plug functions are specific to Sub Block Mode (SBM) David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 20/29] virtio-mem: nb_sb_per_mb and subblock_size " David Hildenbrand
     [not found]   ` <20201016085319.GD44269@L-31X9LVDL-1304.local>
2020-10-16 13:17     ` David Hildenbrand
     [not found]       ` <20201018124104.GD50506@L-31X9LVDL-1304>
2020-10-19 11:57         ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 21/29] virtio-mem: memory notifier callbacks " David Hildenbrand
     [not found]   ` <20201019015724.GA54484@L-31X9LVDL-1304.local>
2020-10-19 10:22     ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 22/29] virtio-mem: memory block ids " David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 23/29] virtio-mem: factor out adding/removing memory from Linux David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 24/29] virtio-mem: print debug messages from virtio_mem_send_*_request() David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 25/29] virtio-mem: Big Block Mode (BBM) memory hotplug David Hildenbrand
     [not found]   ` <20201016093835.GH44269@L-31X9LVDL-1304.local>
2020-10-16 13:13     ` David Hildenbrand
     [not found]   ` <20201019022630.GB54484@L-31X9LVDL-1304.local>
2020-10-19  9:15     ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 26/29] virtio-mem: allow to force Big Block Mode (BBM) and set the big block size David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block David Hildenbrand
2020-10-15 13:08   ` Michael S. Tsirkin
2020-10-12 12:53 ` [PATCH v1 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug David Hildenbrand
     [not found]   ` <20201019034817.GD54484@L-31X9LVDL-1304.local>
2020-10-19  9:12     ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 29/29] virtio-mem: Big Block Mode (BBM) - safe " David Hildenbrand
     [not found]   ` <20201019075406.GE54484@L-31X9LVDL-1304.local>
2020-10-19  8:50     ` David Hildenbrand
2020-10-18 15:29 ` [PATCH v1 00/29] virtio-mem: Big Block Mode (BBM) Michael S. Tsirkin
2020-10-18 16:34   ` David Hildenbrand

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